Spring driven power hammer



Dec. 19, 1967 FERWERDA 3,358,778

SPRING DRIVEN POWER HAMMER Filed Aug. 19, 1965 2 Sheets-Sheet 1 Dec. 19,1967 R. FERWERDA SPRING DRIVEN PQWER HAMMER 2 Sheets-Sheet 2 Filed Aug.19, 1965 FTTORNEYS United States Patent Office 3,358,778 Patented Dec.19, 1967 3,358,778 SPRING DRIVEN POWER HAMMER Ray Ferwerda, 1050 NW.163rd Drive, North Miami, Fla. 33161 Filed Aug. 19, 1965, Ser. No.480,990 3 Claims. (Cl. 173-119) ABSTRACT OF THE DISCLOSURE A very heavyduty hammer suitable for pile driving and pavement breaking includes anelongated cylindrical housing carrying a working tool at the lower endthereof which tool has a shaft extending into the lower end of thehousing and terminating inside of the housing with a blow receiving andtransmitting anvil extension, together with a hammer reciprocatablymounted in the housing toward and away from the anvil extension todeliver repeated blows thereagainst. The hammer has an elongated axialextension which projects out of the upper end of the housing and isthere provided with power means for repeatedly retracting the hammeraway from the anvil and then suddenly releasing it. A two-part helicalspring surrounds the hammer extension and is disposed between the hammerand the upper end of the housing so that the spring means is compressedwhen the power means lifts the hammer, after which the spring meanscauses the hammer to deliver a very powerful blow against the anvil whenreleased by the power means. The novel feature of this invention is thatthe spring means includes at least two separate helical springs in endto end relationship differing from each other in frequency of vibrationsufficiently so that they exert a mutual dampening effect upon springrelease thus preventing destruction of the hammer and its drivingspring.

This invention relates to improvements in a power hammer of a verypowerful character useful for pile driving, pavement breaking and anyother purposes requiring great power.

One of the objects of the present invention is to provide aself-contained hammer comprising a housing with a tool carrying memberextending into the housing at one end, generally the lower end, and withan anvil lying inside of the housing adapted to deliver a blow to thetool carrying member when struck by the hammer. The hammer isreciprocatably mounted in the housing for movement toward and away fromthe anvil. The blow is delivered by a powerful helical spring meanssurrounding a hammer extension and engaged between the hammer and theportion of the housing and always urging the hammer toward the anvil.Power means is carried by the housing and constructed and arranged toengage the end of the hammer extension remote from the hammer, usuallyat the upper end thereof, and to lift the hammer so as to compress thespring and thereafter to suddenly release the hammer extension, wherebythe spring then drives the hammer with great force against the anvil todeliver a blow to the tool.

The present invention is specifically directed to a spring meanscomprising a plurality of helical springs surrounding the hammerextension and concentric therewith and the present invention isdescribed in connection with two such springs, although it will beunderstood that more might be used if desired. One of the difiicultiesin prior devices of this sort related to the vibration of along powerfulspring after it was suddenly released during operation of the hammer.Such vibration was so destructive that the assembly was destroyed withina few hours of use. In the present invention, at least two separatesprings are provided differing from each other in frequency of vibrationsufiiciently so that they exert amutual dampening effect, upon releaseof the compressed springs, thus preventing destruction of the hammer.

Other objects and advantages of the present invention will be set forthin the accompanying drawings and description and the essential featuresthereof will be summarized in the appended claims.

In the drawings:

FIG. 1 is a central sectional view through one embodiment of thisinvention and means for mounting the hammer On a boom carrying vehicleadapted to hold and manipulate the same;

FIG. 1A is a continuation of FIG. 1 at the lower end thereof showing thetool carrying member located below the line A indicated in both figures;

FIG. 2 is a sectional view, enlarged, taken along the line 2-2 of FIG.1;

FIG. 3 is a sectional view taken along the line 33 of FIG. 1;

FIG. 4 is a fragmental sectional line 4-4 of FIG. 2; while FIG.5 is asectional view taken along the line 5-5 of FIG. 2.

Referring to FIG. 1, the hammer of this invention is shown compactlyassembled in connection with a housing which comprises a cylindricalmember 10 carrying at its view taken along the upper end rigid therewitha flange 10a which is secured by means of screws or bolts 11 to ahousing head 12. The cylinder 10 is provided with a head member 13 atits lower end, welded to the cylinder 10, and having a central openingthrough which enters an anvil shaft 14 coaxial with the cylinder 10 andcarrying integral therewith at its upper end the anvil 14a. The anvilshaft 14 passes through a suitable bearing sleeve 15 which is rigidlyconnected to the head member 13 and cylinder 10 by means of gussets 16welded in place. Preferably, a recoil absorbing cushion 17 is providedin the form of a polyurethane annulus surrounding the anvil shaft 14 andlying against the head member 13. It should be understood that the anvilshaft 14 is freely slidable in the head member 13 to carry the anvil 14aaxially of the cylinder 10.

A hammer is provided for delivering a blow to the anvil 14a. This hammeris axially aligned with the anvil and is provided with a hammerextension 19 extending axially upwardly through the cylinder 10,concentrically thereof, and extending axially and out the upper endthereof through a sleeve bearing 20 which is held in proper position bymeans of a bearing cap 21 to which the bearing is welded; and the cap inturn is secured to the lower wall of the housing head portion 12 bymeans of screws or bolts 22. An oil seal 20a prevents leakage oflubricant out of the housing means 12.

A powerful helical spring means, 23a and 23b, approximately one foot indiameter and almost three feet long (for a four to five ton blow)surrounds the hammer extension 19 within the cylinder 10 for compressionbetween the hammer 18 and the bearing cap 21 which lies against lowerend of spring 23a backed up by a'polyurethane cushion 238 lying betweenthe disk 237 and the hammer head 18.

The purpose of the two springs 23a and 23b is to provide at least twoseparate springs dilfering from each other in frequency of vibrationsufliciently so that they exert a mutual dampening effect preventingdestruction of the hammer. While more than two spring members might beprovided in such end-to-end relationship, two such springs aresufficient to provide the improved performance of hammer operationenvisioned by this invention. The springs 23a and 23b have parameters oflength, diameter, pitch, number of working coils, diameter of springwire and torsional modulus of elasticity and the two springs must differfrom each other in at least one of these parameters sufficiently tocause the above mentioned dampening effect. In one embodiment the spring23a has a length of twenty inches, a diameter of twelve inches, sevenworking coils, three inch pitch, and a spring rod material 1% inches indiameter. The spring 21% has a length of 13 /2 inches, a spring diameterof 11% inches, six working coils, 2 /2 inch pitch, and spring rodmaterial 1% inches in diameter. The torsional modulus of the elasticityof the two springs may be varied by varying the analysis of the steelslightly or by changing the tempering of similar steels so as to cause avariation in the two springs.

In carrying out this invention, any suitable means may be provided forlifting the hammer to compress the springs 23:: and 23b and thereafterto release the hammer so that the springs cause a tremendous blowagainst the anvil head 14a. The lifting means here shown comprises aT-shape member 24 having a vertically extending central bore which fitson a reduced diameter portion 19a of the hammer extension whichterminates at a shoulder 1% against which the T -shape member 24 rests.A nut 25 holds the member 24 in position. The T-shape mem ber haslaterally extending arms 2411 on opposite sides thereof for the purposeof engagement by a lifting device about to be described.

The power means for lifting the hammer extension comprises an hydraulicmotor 26 bolted to the wall of the housing head means 12 and suppliedwith hydraulic power through flexible tubular connections 27 and 28 fromany suitable source. This motor terminates in a drive shaft 29 whichextends vertically downwardly into the housing 12 for rotation of aunitary worm 34 which in turn meshes with a cone drive worm gear 35 witha mechanical advantage of about twenty to one. The worm gear 35 is keyedto a shaft 36 which in turn is journaled in bearing 37 carried bysuitable bearing caps 38 secured to the housing 12. Keyed to the shaft36 are a pair of pinions 39 each of which is aligned with a gear wheel40 meshing with the pinions 39 and having a mechanical advantage ofapproximately three to one. Each of the gear wheels 40 is keyed to ashaft 41 which is journaled in suitable bearings 42 carried by thebearing caps 43 in the housing 12. A pair of cam rollers 44 are securedto each of the gear wheels 40 diametrically opposite to each other bymeans of stub shafts 44a and held in position by nuts 45 and suitablelock washers. The cam rollers 44 on each gear wheel are aligned toengage beneath the opposite arms 24a of the T-member 24 so as to liftthe hammer extension 19 and the hammer head 18. It will be noted in FIG.1 that each cam roller 44 in the dotted position of FIG. 1 engagesbeneath one of the T-shape arms 24a toward the left side thereof andlifts the T-shape member while the cam roller 44 moves through an arc ofslightly more than ninety degrees causing the cam roller to reach thedot-dash position of FIG. 1 after which it rolls out of contact with thearm 24a, thus releasing the arm suddenly so that it is urged downwardlyimpelled by springs 23a and 23b which in this embodiment is compressedapproximately ten inches of its total vertical length.

It should be understood that a suitable tool 46 is carried at the lowerend of anvil shaft 14. The tool will depend upon the kind of work to beperformed. The tool attachment of this embodiment is clearly shown inFIG. 1A.

Stop means is provided on the anvil shaft 14 to prevent it being drivenup inside of the cylinder 10 so that the anvil head 14a always remainsspaced below the blow delivering hammer 18. This stop is shown at 49 andcomprises a split collar threaded on the shaft 14 and held in positionby bolt 50. This collar will strike the lower end of the bearing sleeve15 on the rebound after a blow is delivered so as to stop the upwardmotion of the anvil member 14a. Preferably, but not necessarily, arecoil spring 51 is provided surrounding the shaft 14 and held betweenthe collar 49 and the bearing 15 to cushion the recoil at this pointafter a blow is delivered.

The collar 49 may be provided with means for preventing rotation of thetool 46 about its own axis if desired. Such a device is shown as a bar52 rigidly welded to the housing cylinder 10 and extending freelythrough a hole 48a in the collar 49.

Means may be provided if desired for holding the hammer of thisinvention and for manipulating the same from a boom 53 which may be ofany suitable type but is here shown as a telescopic boom of a vehicleshown in United States Patent No. 2,541,045, granted to Ray and KoopFerwerda, Feb. 13, 1951. Bearing caps 54 are bolted to boom 53 andjournal a shaft 55 which carries a crank arm 56 which in turn ispivotally connected to a clevis rod 56 controlled by a piston 57reciprocatable in cylinder 58 on the boom 53 by suitable hydraulic fiuidsupply means. Movement of piston 57 will tilt the hammer about shaftpivot 55. Welded to shaft 55 are a pair of parallel cars 60 in turnwelded to a sleeve 61 in which the cylinder 10 is held snugly but freelyreciprocal in a vertical direction as blows are delivered. To hold thecylinder 10 from rotating the sleeve 61, a vertical bar 62 is welded tothe flange 10a at the top and to a collar 63 at the bottom, which inturn is bolted to the cylinder 10 at 64. Parallel flanges 65 welded tosleeve 61 on opposite sides of bar 62 prevent relative rotation at thispoint.

The mechanism herein described provides approximately a ten inch strokeof the hammer from sixty to seventy-five times per minute, thusdelivering eight to ten thousand foot pounds for each blow or slightlyover five hundred to six hundred thousand foot pounds per minute.

Power hammers of the type herein described previously known in the priorart and utilizing a single spring in place of the springs 23a and 23btore themselves apart in a relatively few hours of operation. The reasonfor this apparently lay in the powerful forces released when a springalmost three feet long and a foot in diameter and made of heavy springwire or rod in the neighborhood of 1% to two inches in diameter suddenlyreleased tremendous vibratory forces. The present invention seems toovercome this problem because the springs 23a and 23b differ from eachother in frequency of vibration sufficiently so that they exert a mutualdampening elfect after the spring means is released to deliver a blow ofthe hammer on the anvil.

What is claimed is:

1. A pile driving and pavement breaking hammer comprising a housing; atool-carrying member having a shaft extending into said housing at oneend thereof; said shaft having a blow receiving and transmitting anvilextension disposed within said housing; a hammer reciprocatably mountedin said housing for a stroke movement in line with said shaft toward andaway from said anvil extension; said hammer having an elongatedextension coaxial with said shaft and extending in said housing awayfrom said hammer and said anvil extension; a helical spring meanssurrounding said hammer extension and disposed between said hammer andthe end of said housing opposite said one end; said spring meansincluding at least two separate helical springs in end to endrelationship differing from each other in frequency of vibrationsufficiently so that they exert a mutual dampening effect upon releaseof the loaded spring means and prevent destruction of the hammer andspring means; said spring means delivering a blow ofspring-meansdestructive force when delivered by a single spring; a rigidwear plate between said two separate springs and holding themconcentric; and power means carried by said housing including meansrepeatedly retracting said hammer extension and said hammer against thebias of said spring means and then suddenly releasing them, in use ofsaid hammer, thereby permitting said spring means to cause said hammerto deliver sequential blows against said anvil extension.

2. A hammer as defined in claim 1 wherein said two separate springs haveparameters of length, diameter, pitch, number of working coils, diameterof spring wire and torsional modulus of elasticity, differ in at leastone of said parameters.

3. A hammer as defined in claim 2 wherein said two and said springs 1springs have approximately the same means diameter and arelongitudinally aligned so that their vibratory forces substantiallydirectly oppose each other.

References Cited UNITED STATES PATENTS 1,244,386 10/1917 Spehar 173-119X 1,356,556 10/1920 Payne 173-119 X 2,110,957 3/1938 Kollock 173-119 X2,225,531 12/1940 Charles 173-119 X 2,772,858 12/1956 Galvez 173-119 X3,276,760 10/ 1966 Last et al. 267-1 X FRED C. MATTERN, JR., PrimaryExaminer. L. P. KESSLER, Assistant Examiner.

1. A PILE DRIVING AND PAVEMENT BREAKING HAMMER COMPRISING A HOUSING; ATOOL-CARRYING MEMBER HAVING A SHAFT EXTENDING INTO SAID HOUSING AT ONEEND THEREOF; SAID SHAFT HAVING A BLOW RECEIVING AND TRANSMITTING ANVILEXTENSION DISPOSED WITHIN SAID HOUSING; A HAMMER RECIPROCATABLY MOUNTEDIN SAID HOUSING FOR A STROKE MOVEMENT IN LINE WITH SAID SHAFT TOWARD ANDAWAY FROM SAID ANVIL EXTENSION; SAID HAMMER HAVING AN ELONGATEDEXTENSION COAXIAL WITH SAID SHAFT AND EXTENDING IN SAID HOUSING AWAYFROM SAID HAMMER AND SAID ANVIL EXTENSION; A HELICAL SPRING MEANSSURROUNDING SAID HAMMER EXTENSION AND DISPOSED BETWEEN SAID HAMMER ANDTHE END OF SAID HOUSING OPPOSITE SAID ONE END; SAID SPRING MEANSINCLUDING AT LEAST TWO SEPARATE HELICAL SPRINGS IN END TO ENDRELATIONSHIP DIFFERING FROM EACH OTHER IN FREQUENCY OF